Horn vs. Waveguide

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#401
gedlee said:



This is incorrect. I agree with Mr. Linkwitz completely on this point. Stated another way - the axial response and the power response need to track one another. However, it is a misnomer that dipoles do this because they don't. A dipole has a changing directivity with frequency just as a direct radiator does, it's just that the dipole has an aditional Cos(theta) factor that the baffled piston doesn't. This additional factor is dominate at LF but the drivers directivity is dominate at HF. Only waveguides can approach the equivalence of direct and reverberant frequency response.
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You horns or 'waveguides' with their monopole woofers do exactly what you you claim to be wrong.
 
#402
gedlee said:



This is incorrect. I agree with Mr. Linkwitz completely on this point. Stated another way - the axial response and the power response need to track one another. However, it is a misnomer that dipoles do this because they don't. A dipole has a changing directivity with frequency just as a direct radiator does, it's just that the dipole has an aditional Cos(theta) factor that the baffled piston doesn't. This additional factor is dominate at LF but the drivers directivity is dominate at HF. Only waveguides can approach the equivalence of direct and reverberant frequency response.
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Puting it this way, I think I'm getting a better feeling why one would want controlled directivity instead of dipole or omni-directional. With a well controlled roll-off from on-axis to way off-axis, the energy of early reflections are lower.

ZilchLab said:


How are they different? That's the very definition of constant directivity and uniform power response, no?

Outside the controlled sound field, however, we WANT it to fall away quickly to achieve an element of independence from the character of the room. We're not doing omnidirectional here; the objectives are different.

I can find my coffee cup in the impulse response. I'm not going to tune the system to it, though.

[Not my beer bottle, either.... 😀 ]
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Well, the ultimate objective is to have as realistic reproduction of the recorded program as possible. It does seem that the controlled directivity approach has some advantage in small rooms.

I am curios as to what is causing the impulse to be the way it is.😕 If it's the compresson driver, then probably I would look for other drivers.
 
#403
soongsc said:
Well, the ultimate objective is to have as realistic reproduction of the recorded program as possible. It does seem that the controlled directivity approach has some advantage in small rooms.
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I believe so, yes, and I'd like for the result not to be variable depending upon how wide the drapes are open on one side of the room.

At the other extreme, the "loudspeakers as headphones" approach is not very satisfactory, either. There's an optimum balance somewhere in between.... :yes:

soongsc said:
I am curios as to what is causing the impulse to be the way it is.😕 If it's the compresson driver, then probably I would look for other drivers.
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It's reflections. Rooms and the stuff in them generate them.

Ideally, I'd like to minimize those generated within the system itself, presumably, but it's got to work in "real" space, as well....
 
#404
soongsc said:
I am curios as to what is causing the impulse to be the way it is..😕 If it's the compresson driver, then probably I would look for other drivers.
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It's a combination of the diaphragm, phase plug, diaphragm surround, driver exit and in the gedlee case your questioning the horn'guide', crossover and foam.
 
#406
ZilchLab said:


...

It's reflections. Rooms and the stuff in them generate them.

Ideally, I'd like to minimize those generated within the system itself, presumably, but it's got to work in "real" space, as well....
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Well, I'm talking about the leading part of the impulse. If it's caused by the compresson driver, then that is what needs to be fixed. Gedlee had mentioned the criticality of thoat matching, I think that would also be very difficult to solve when matching direct radiating drivers to a thoat.
 
#407
Magnetar said:


Or if the drapes are in front of the speaker?
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Grilles and perf screens in the path are certainly elements for analysis.

The whole room treatment thing is a recipe for madness, in my book; I'd prefer not to have to build a room that "works" and be tweaking that for the rest of my life because it doesn't.

Constant directivity tips the odds in my favor.... :up:
 
#408
ZilchLab said:


I believe so, yes, and I'd like for the result not to be variable depending upon how wide the drapes are open on one side of the room.

At the other extreme, the "loudspeakers as headphones" approach is not very satisfactory, either. There's an optimum balance somewhere in between.... :yes:

It's reflections. Rooms and the stuff in them generate them.

Ideally, I'd like to minimize those generated within the system itself, presumably, but it's got to work in "real" space, as well....
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Monopole multi sources up to 200Hz, Cardioid cones up to 1000Hz, controlled directivity up to 15-20kHz. That seems a good plan to me.
 
#409
soongsc said:

Well, I'm talking about the leading part of the impulse. If it's caused by the compresson driver, then that is what needs to be fixed. Gedlee had mentioned the criticality of thoat matching, I think that would also be very difficult to solve when matching direct radiating drivers to a thoat.
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I have been using compression drivers since 1976 and have to say good luck finding one with a pretty impulse response. -
 
#410
soongsc said:

Well, I'm talking about the leading part of the impulse. If it's caused by the compresson driver, then that is what needs to be fixed. Gedlee had mentioned the criticality of thoat matching, I think that would also be very difficult to solve when matching direct radiating drivers to a thoat.
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Sorry, I thought you were referring to my beer bottle. 😉

Here's some info on the other. There's a phase plug to make it happen:

http://www.jblpro.com/ae/pdf/CMCD TechNote.pdf
 
#411
Magnetar said:

The gedlee speaker has to used behind a curtain according them.
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That's the WAF thing.

Both your and my systems could use a bit of that.

Bling is sometimes a workable alternative.... 😛
 

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#412
Dr. Geddes said that it is just a win win situation for HT (the drapes thing). You don't have to stare at big 45deg toed in cabinets when watching a movie, plus you get an upper spectrum tilt that is friendly to our non CD sonic world experience.
 
#413
Magnetar said:


Come on, your no fun - tweaking is a good thing.

The gedlee speaker has to used behind a curtain according them.
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Magnetar said:


His reference to the drape was not to cosmetics but the fact they will not perform properly unless behind the drapes. Kinda like the Wizard of Oz
An externally hosted image should be here but it was not working when we last tested it.
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Do you have a reference to said statement? I read he mentioned to use behind curtain so that WAF was not an issue. In his living room (I visited once) he had a pair of Summas without curtains in front.
 
#416
ZilchLab said:
Well, that's a fundamental uniqueness of horns vs. waveguides.

They can be configured to have a "Presence."
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That's not too clear- a true waveguide ( the definition of a waveguide according to the inventor) has NEVER been built.

A horn can be made to have presence - and there are lots and lots of them around
 
#419
Magnetar said:



What did it look like? A male or female? Was it naked? Got any pictures you'd like to share?
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I am talking about the speaker (picture attached on post #414). I think the speaker is a he, and is indeed naked. He looks a bit chilly, and I think we need to give him a big hat. I am wondering if his matching mate is a she. But it is OK, if it is a he too.
 
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